Project ForgeSign up free
Chemical Reaction Engineering
Reaction Kinetics
GATE 2011
Hard

Reactant R forms three products X, Y and Z irreversibly, with rX=kXCR, rY=kYCR^1.5, rZ=kZCR. The activation energies for formation of X, Y and Z are 40, 40 and 5 kJ/mol respectively. The pre-exponential factors for all reactions are nearly the same. The desired conditions for MAXIMIZING the yield of X are

  • Ahigh temperature, high concentration of R
  • high temperature, low concentration of R
  • Clow temperature, high concentration of R
  • Dlow temperature, low concentration of R

Explanation

X vs Z (both order 1, so CR cancels in the ratio): since EaX(40)≫EaZ(5), rX/rZ increases with temperature — favor HIGH temperature. X vs Y (Y is order 1.5, higher than X's order 1): rX/rY∝1/CR^0.5, so this ratio increases as CR decreases — favor LOW concentration of R. Combined: high temperature, low concentration of R.

Source: GATE CH 2011 (2011)

This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.

Start revising free